I don't know anything about MTF charts and the few times I've read the results it never matched up in the real world.

The Contax Zeiss lenses I use don't rate that high by most reviews, but they're sharp, almost too sharp but I think they're pretty and pretty is what it's all about.

Also I've never understood that a certain lens has to be used for a certain genre. Sure if your shooting retail fashion you probably won't to compress a subject a little more than normal,but like anything in life, there are no real rules.

This was shot with an Aptus 22 using a 45mm Hartblei which no one would consider a traditional portrait lens

This also with an Aptus 22 with a 80mm Zeiss. and the next with a Zeiss 80mm on a p30+

And this with a Leica 24 on a M8 which means the crop makes it something like a 35 lens on a full frame 35 camera

Whatever looks pretty to the photographer works, the rest is just numbers.

To some the numbers are important and I can respect that, but to me it's just what it looks like that matters.

In reality, if you want to subtly change the look of a lens, if the scene permits, just pull back or get closer.

Regarding lenses, sharpness depends on how exact you focus. I have recently tested an old Sonnar 150/4 and performed very well on 24 MP APS-C. That lens has very good MTF and it performed accordingly. I even measured MTF and got very close to the published values, but I think this may have just been a coincidence. I used this lens because it was about second in sharpness among the classic lenses and I got a copy at very low cost. I may also add that my copy is very sensitive to lens flare.

I would say that MTF values describe the lens very well, but only at optimal focus. I do understand that lens makers base their designs on MTF but calculate dozens of MTF graphs for different focusing distance, defocus and also different spectrum of light.

I don't know anything about MTF charts and the few times I've read the results it never matched up in the real world.

The Contax Zeiss lenses I use don't rate that high by most reviews, but they're sharp, almost too sharp but I think they're pretty and pretty is what it's all about.

Also I've never understood that a certain lens has to be used for a certain genre. Sure if your shooting retail fashion you probably won't to compress a subject a little more than normal,but like anything in life, there are no real rules.

This was shot with an Aptus 22 using a 45mm Hartblei which no one would consider a traditional portrait lens

This also with an Aptus 22 with a 80mm Zeiss. and the next with a Zeiss 80mm on a p30+

And this with a Leica 24 on a M8 which means the crop makes it something like a 35 lens on a full frame 35 camera

Whatever looks pretty to the photographer works, the rest is just numbers.

To some the numbers are important and I can respect that, but to me it's just what it looks like that matters.

You know, the explanation in there about keeping quality via lens symmetry with short registration distance (biogon) really sells the NEX with it's 18mm distance. I was looking for a good wide angle camera expecting to use my lenses on the FF A99 or it's successor. If I can get a FF NEX with top quality wide lenses it saves me a lot of money. I was even considering going Nikon D800 for wide and Sony for medium to telephoto APS-C.

I could even put the Canon T/S wide on it. I think my next camera will be NEX!

It's not that simple, unfortunately. The symmetric wide angles have large "chief ray angle" which doesn't play well with present day FSI (Front Side Illuminated) sensors and micro lenses. Leica did some compromise on the M8 and somewhat less compromise on the M9 to work well M series lenses. Leica uses offset microlenses and thin IR filter for that reason.

If you google for "lens cast" you may find a lot of information. Some of the issues can be handled in software.

I don't know which top quality wide angles you need.

I have:

Sony ZA 24-70/2.8 (OK at f/8 all way out to corners, f/2.8 large sweet spot with weak corners)Sigma 12-24/4.5-5.6 (Awful corners at 12 mm, almost usable 14-24 mm)Samyang 14/2.8 (Almost OK across field at f/2.8, perfect at f/8, but this is a totally manual lens)Minolta 20/2.8 (OK if stopped down to f/11)

You know, the explanation in there about keeping quality via lens symmetry with short registration distance (biogon) really sells the NEX with it's 18mm distance. I was looking for a good wide angle camera expecting to use my lenses on the FF A99 or it's successor. If I can get a FF NEX with top quality wide lenses it saves me a lot of money. I was even considering going Nikon D800 for wide and Sony for medium to telephoto APS-C.

I could even put the Canon T/S wide on it. I think my next camera will be NEX!

The Phase "Schneider" 55mm LS 2.8 is a 15/30/60 graph while the data for the Contax is 10/20/30

And here is the Contax 645 chart extrapolated to 15/30 overlaid on theThe Phase "Schneider" 55mm LS 2.8 is a 15/30/60 graph

It is quite apparent that the old Contax lens is sharper and more uniform than the Phase "Schneider".Interesting that a lens about 15 years old outperforms a lens designed more than 10 years later and is far more expensive.

I assume that it's clear to most readers that some commenters on this thread have sufficient backgrounds in lens design, optical quality testing, historical variations in MTF notations and derivation methods (along with the requisite background in photography to translate the numbers into what they do and don't tell you about the real world photographic result), to properly analyze the MTFs of these lenses while others do not.

Kudos to BCooter: he knows what he knows (a ton, especially how to make gorgeous images and run a successful image-making business) and knows what he doesn't know (some of the uber tech theory stuff), which allows him to provide an informative post that benefits the community. Above all he does not pretend to be an expert in areas that he is not. Respect!

It is quite apparent that the old Contax lens is sharper and more uniform than the Phase "Schneider".Interesting that a lens about 15 years old outperforms a lens designed more than 10 years later and is far more expensive.

Dear Fred,

Have you shot and compared both lenses in a variety of circumstances? Or are you making your analysis through MTF charts alone?

Comparing two MTF charts from two different manufacturers a decade apart without knowing what criterium were used in their creation (other than cycle rates), and adding a pseudo interpolated curve for one of them, is, to put it mildly, an insufficiently thorough way of comparing two lenses for any given use.

More to the point I suggest shooting pictures with the lens in situations similar to how you would use it and then looking at the pictures to see if they suit your fancy, and how they compare to other viable options. What a crazy idea right?

Correcting misinformation on LL (nearly all from the same witch-hunter source) has become bad for my mental health and wellbeing.

I don't think anyone could fault the Schneiders for being soft or having a displeasing image. Also, the Contax 55mm is an f/3.5 lens, I would sure hope that it renders sharper if both of those MTF graphs are for the lenses wide open.

Which 645 lenses would you say are so bad as to be unusable or a waste to use on a 60/80mp back?

I don't think anyone could fault the Schneiders for being soft or having a displeasing image. Also, the Contax 55mm is an f/3.5 lens, I would sure hope that it renders sharper if both of those MTF graphs are for the lenses wide open.

Which 645 lenses would you say are so bad as to be unusable or a waste to use on a 60/80mp back?

Both are at f8. Also there is very little difference between an f2.8 and an f3.5 lens. It's only 1/3rd of a stop.

Have you shot and compared both lenses in a variety of circumstances?Or are you making your analysis through MTF charts alone?

Comparing two MTF charts from two different manufacturers a decade apart without knowing what criterium were used in their creation (other than cycle rates), and adding a pseudo interpolated curve for one of them, is, to put it mildly, an insufficiently thorough way of comparing two lenses for any given use.

"Have you shot and compared both lenses in a variety of circumstances?" Yup enough."Or are you making your analysis through MTF charts alone?" Nope.

I don't know what you mean pseudo interpolated .... I said extrapolated.

While there are differences in MTF graphs from different manufacturers they are still a good indication if youknow how to read them and take into consideration the modulation frequency.

However in this case the differences between manufacturers is not that relevant as the main issue here is the roller coastergraph of the Phase One lens. A curve may be overall shifted up or down but different testing methods, but the relative heightacross the curve (roller coaster) would not change. The differences across the frame of the 55 2.8 LS is very significant.As can be seen with the 55mm 2.8 the Schneider Logo on the lens is not a guarantee of state of the art quality.

Have you shot and compared both lenses in a variety of circumstances? Or are you making your analysis through MTF charts alone?

Comparing two MTF charts from two different manufacturers a decade apart without knowing what criterium were used in their creation (other than cycle rates), and adding a pseudo interpolated curve for one of them, is, to put it mildly, an insufficiently thorough way of comparing two lenses for any given use.

More to the point I suggest shooting pictures with the lens in situations similar to how you would use it and then looking at the pictures to see if they suit your fancy, and how they compare to other viable options. What a crazy idea right?

Correcting misinformation on LL (nearly all from the same witch-hunter source) has become bad for my mental health and wellbeing.

Not a crazy idea at all. Actually one of my points is to compare the overpriced 55 2.8 LS to the respectable and older Mamiya 55mm 2.8It's also a good idea to look at MTF graphs before taking test photos and looking to see if weaknesses indicated by the MTF graphsare an issue for you in practice.

It's really silly when dealers and fan boys dismiss MTF graphs when they are used by every lens manufacturer to test and develop their lens designs.

Kudos to BCooter: he knows what he knows (a ton, especially how to make gorgeous images and run a successful image-making business) and knows what he doesn't know (some of the uber tech theory stuff), which allows him to provide an informative post that benefits the community. Above all he does not pretend to be an expert in areas that he is not. Respect!

AND guess what ... he uses old Contax lenses and the Contax 645 with his digital back. He even shot the Phase One campaign with his old Contax lenses and Contax 645

Not a crazy idea at all. Actually one of my points is to compare the overpriced 55 2.8 LS to the respectable and older Mamiya 55mm 2.8

Anyone that's actually owned and used both the older Mamiya 55mm 2.8 and the newer 55mm LS knows that there is a world of difference between the two lenses. The old 55mm is a "throw-away" lens by comparison. But maybe that's just me as my experience has been with using both lenses on the P65+ and IQ180. The old 55mm was okay with much older MFDBs, and ahem, film. And overpriced compared to what? Sorry, but I disagree. The 55mm LS is a solid investment and a good performer. I don't expect every Phase or SK lens that I buy to perform in the rarified air of the 150mm D, but that apparently is the standard you expect here of every Phase lens. It seems every manufacturer has their "star" but I think it's unreasonable to hold that star-status standard to every other lens in the line and be objective, well, I guess unless your experience is limited to few months of shooting a Phase P25+ before abandoning the system and some obsessive witch-hunt mentality compels you to attack all-things Phase ad nauseum. Extrapolate all you want. When you enter your deep-seated bias into the equation it's just not helpful, and actually misleading imho.

Imagine using a lens (especially if you think it's *ahem* overpriced) before you make a decision to purchase/invest. Maybe actual experience will give you a better idea if a lens will work for you or not. MTF charts always had limited value to me. Actually using a lens. Wow, what a crazy concept that is Doug!

The insinuation that "dealers" responding here are automatically biased is really offensive, particularly since they do have reputations for being fair, helpful, and transparent. And then to call all others that actually have real life experience using medium format digital products for years (including Phase) "fan boys" is even more offensive, particularly when cast against someone who has an obvious axe to grind in a childish witch-hunt fashion against Phase One (and medium format digital), while having little if any real experience with the equipment in question. Buying an old used P25+ digital back off of Ebay and then using it for oh, say 562 exposures/shots really doesn't count for much, though I guess it allows you can say, "I have owned and used a Phase digital back." The overriding question that crosses my mind: Is there really anything positive that this anti-Phase / witch hunt brings to this forum?

Why are you extrapolating the contax 30 line on the second graph when you have overlain the original in the first graph ? Secondly, why is the extrapolated 30 contax line showing higher resolution (placed higher on the y-axis) when in the first graph the Schneider 30 line generally tends to out-resolve the contax 30 ?

The Phase "Schneider" 55mm LS 2.8 is a 15/30/60 graph while the data for the Contax is 10/20/30

And here is the Contax 645 chart extrapolated to 15/30 overlaid on theThe Phase "Schneider" 55mm LS 2.8 is a 15/30/60 graph

It is quite apparent that the old Contax lens is sharper and more uniform than the Phase "Schneider".Interesting that a lens about 15 years old outperforms a lens designed more than 10 years later and is far more expensive.

AND guess what ... he uses old Contax lenses and the Contax 645 with his digital back. He even shot the Phase One campaign with his old Contax lenses and Contax 645

And the point?

This is a pretty misleading statement. I don't think anyone but old Cooter can tell you why he uses an old Contax. Maybe it's because he likes it? It smells nice? Dunno. But your insinuation here is that James uses the old Contax because he doesn't like the Phase DF or the performance of the line of lenses. I just didn't get that from Cooter's post. I think the best part that makes sense from Cooter is, "Whatever looks pretty to the photographer works, the rest is just numbers."

This is a pretty misleading statement. I don't think anyone but old Cooter can tell you why he uses an old Contax. Maybe it's because he likes it? It smells nice? Dunno. But your insinuation here is that James uses the old Contax because he doesn't like the Phase DF or the performance of the line of lenses. I just didn't get that from Cooter's post. I think the best part that makes sense from Cooter is, "Whatever looks pretty to the photographer works, the rest is just numbers."

What I wrote isn't insinuating anything.... simply that he uses older Contax lenses and loves them.

Why are you extrapolating the contax 30 line on the second graph when you have overlain the original in the first graph ? Secondly, why is the extrapolated 30 contax line showing higher resolution (placed higher on the y-axis) when in the first graph the Schneider 30 line generally tends to out-resolve the contax 30 ?

Paul

Here are all three sets overlaid... should clear it up for you.

Red is Contax 10/20/40Black is Phase "Schneider" 15/30/60Blue is the extrapolated curve averaging the Contax 10/20 for 15 and 20/40 for 30.